Field of the Invention
The present invention relates generally to the field of fiber optics, and in particular to applications for multicore optical fiber cables and connectors.
Background Art
The growing need for high-speed applications in the structured cabling market continues to spawn interest in optical fiber distribution systems. Legacy copper patching systems continue to be replaced by fiber-optic systems, as bandwidth demands increase. In data centers, central offices, and other structured cabling applications, fiber-optic patch panels are being widely deployed to facilitate connections between switches, servers, storage devices and office space.
In structured cabling systems, it is very desirable to provide fiber distribution frames with increased connector-port density. As used herein, the term “density” refers to the number of locations, per unit volume or unit area, for providing connections on a distribution frame.
A distribution frame is typically configured to include multiple shelves of a specified size. The term “rack unit” (abbreviated simply as “U”) refers to a height of 1.75 inches. Thus, a shelf height of 7 inches corresponds to a rack unit height of 4U. The density of a shelf can thus be quantified as the number of optical paths, or channels, per rack unit (e.g., 36 channels/U).
In order to reduce the effective area that a patching system utilizes in a facility, suppliers of fiber optic cables and connectivity have taken steps to reduce the size of the fiber optic connectors. For instance, LC connectors, which are 50% smaller than SC connectors, have become prevalent in the market place. Simply converting to LC connectors, from SC, immediately provides a two-fold increase in patching density.
Pre-terminated modular cassette patching products are available for use in structured cabling applications. A typical cassette provides a plurality of simplex connector adapters (i.e., sockets) at its front end and one or more multifiber connector adapters (e.g., MPO-type) at its back end. The front and back adapters are connected to each other within the cassette housing, by fiber optic fanouts.
These cassette systems allow a user to create a passive network link with minimal fiber optic expertise. An installer loads a cassette onto a termination shelf within a vertical rack cabinet. A multifiber-MPO-terminated trunk (backbone) cable is then plugged into an adapter at the rear of the cassette. An optical transceiver can then be connected into the network by plugging one end of a patchcord into transceiver socket, and plugging the other end of the patchcord into an adapter at the front of the cassette. An optical link can be completed by performing the same steps at the other end of the trunk cable.
Modular cassettes are commonly installed in a side-by-side configuration on a termination shelf. If a 1U panel has a terminal shelf configured to receive three side-by-side modular cassettes, each housing 24 LC connectors, the port density is 72 channels/U (i.e., 24×3).
A significant improvement in density has been achieved by increasing the number of conventional pre-terminated modules that can be installed into a panel or shelf. For example, by using a 24-port LC module with low-profile latches, it is possible to install four modules into a 19″ horizontal 1U panel, instead of only three. The channel density thus increases from 72 channels/U (i.e., 24×3) to 96 channels/U (i.e., 24×4), a 33⅓ percent increase.
Although the increases in density achieved by increasing the number of modules is noteworthy, it does not, in itself, fully address the rising demand for increased densities, lower power consumption, faster transmission rates, and the like. Jamming more components into a confined space, reducing connector size, and other such approaches make assembly, installation and handling more challenging. A solution is needed that does not adversely affect fiber management.